A sharpener of the above kind is described, for example, in DE 38 24 883, and comprises a sharpener housing generally molded as a one-piece unit and made of a plastic material. The sharpener housing defines a guide channel for receiving a front end of the pencil therein, which channel tapers conically in an insertion direction of the pencil. A sharpener blade is held in the sharpener housing and is disposed so as to be tangential with respect to the guide channel. The sharpener housing further defines a free space therein in the insertion direction of the pencil, the free space adjoining the guide channel for receiving a core tip of the pencil therein. In a sharpener of the aforementioned kind, the free space is open toward a top and a bottom of the housing, the free space being further limited by a stick-type shaping cutter having a bow-shaped blade and further defining a triangular cross section which, together with the open configuration of the free space at the top and bottom of the housing, is intended to allow a regular cutting of the core for shaping the same while avoiding scrape-offs. The free space is particularly intended to prevent the cuttings from being acted upon by the sharpener blade in order to avoid smearing of the cuttings in the case of a pile-up resulting from the problematic soft consistency of the core material.
The above configuration, however, disadvantageously leads to a low inherent stability or a low resistance to deformation of the stick-type shaping cutter. As a result of the above, given the varying degrees of softness of the cores used in known cosmetic pencils, the shaping cutter described above tends to sometimes scrape the cores instead of cutting the same. However, cutting is a desired step when shaping the core tip of pencils with the above shaping cutter.
In DE-B-1 236 374, a soft-core sharpener is disclosed having a shaping cutter which is used to shape the core tip of the pencil and which is configured as a narrow metal strip adapted to act upon the tip of the soft core with its arcuate front edge in a direction which is essentially at a right angle to the surface of the tip. The resulting scraping of the soft core leads to a pile-up of the soft core material in a region of the shaving edge. This pile-up causes a smearing of the groove in the sharpener base, which smearing has a negative effect on the core tip, the core tip tending to be very sensitive, particularly for cosmetic purposes.
Finally, DE-U-80 07 479 discloses a sharpening box for the truncated-cone sharpening of the lower shaft end of candles. The sharpening box is designed such that the candle base can be inserted into smaller receiving openings in candle holders, and defines a conical guide channel for the candle base which is slotted in the longitudinal direction thereof. One of the edges of the slot is configured as a shaving knife having a wedge shaped cross section in a plane perpendicular to the longitudinal axis of the guide channel. The wedge tip of the wedge shaped cross section projects as a shaver essentially tangentially into the guide channel of the sharpening box. The shaved off candle material glides along an edge of the slot and falls, without being further guided, into a receptacle at an exterior region of the channel wall. The shaping of the candle base as described above occurs in a circumferential region of the candle shaft, which region presents no space problems, contrary to the soft core tip region of a cosmetic pencil. For that reason alone, the removal of the candle material presents no particular problems.